The lifetime of a star is too easy steps that have in fact been calculated, though badly, by science fiction authors. the first step is the mass luminosity - the lifetime of the star - which of course is the main sequence of the star. this is based on the work of Eddington, and works out to a curve. the next bit is how long that life can develop on the stars surface. this, of course, has variables which we do not know. but this is not really a this advantage, we still use Newton's rules even though in his time they did not know about fusion, and thought the sun was warm by gravity.

We can however make calculations that will tell us the minimum length of time - though it can be shorter based on later discoveries. the minimum length of time is our own solar system, scaled up to the minimum length of time needed to get to our level of sophistication.

Is the mass luminosity scale, and all that is needed is to insert the largest known time in to the equation - that is what is the largest known luminosity that will get to break out of the solar system. Since this is not until star death, but rather until the star swells up by consuming helium rather than hydrogen, one can easily see that it is about 1.3 solar masses. At which point the life form will have to go to another body, in the same solar system, at which point they will have a few million years to figure out how to go fast enough to find another solar system.

As we explore the known universe, we can reduce this number has we find new forms of life which can leave earlier - we have only a few examples, and we take the most useful example ( namely us) and set it on the fastest star possible. This includes having a moon, because that accelerates the possibility by making it faster to escape.

What this should tell us, is that we are on the cutting edge of life, though many more will pass through. we are not the first, but we are in the crowd that will be among the first.